Piston expander and pin noise eliminator



Sept. 1, 1942. D. M. SOLENBERGER PISTON EXPANDER AND' PIN NOISE ELIMINATOR Filed May 19, 1939 IN VENT OR. .pzw/mozf/vafwfe ATTORNEY5 Patented Sept. 1, 1942 PISTQN EXPANDER, AND PIN NOISE ELIDIINATOR Dean M. Solenberger, Cleveland, Ohio, assignor to Simplex Products Corporation, Cleveland} Ohio, a corporation of Ohio Application May 19, 1939, Serial No. 274,605 io'claims. (01. 309-12) This invention relates to pistons or' the like and more particularly to an improved piston expanding device for eliminating piston slap in I all kinds of pistons and at the same time quieting piston pin noise.

In the operation of internal combustion engines the pistons and cylinders frequently become Worn to such an extent that objectionable looseness of thelpistons in the cylinders occurs with resulting piston slap. Numerous devices have been employed for expanding the skirt of a piston to make it fit more tightly in the cylin-v der and thus remove the noise and improve the performance of the engine. Most of these devices have been designed for, and useful only in, pistons having split skirts, the usual action of the expander being to spread apart the edges of the split skirt portion to increase the effective diameter of the piston.

It is an object of my present invention to provide a piston expanding device which is particularly useful for removing piston slap in solid skirt pistons but which may also be used for removing slap in slotted skirt pistons. Other objects of my invention are the provision of a piston expanding device which not only will increase the effective diameter of the piston but which will quiet or completely eliminate piston pin noise where such noise occurs due to looseness of the piston pin in its bearings in the piston; the provision of a combined piston expander and pin noise eliminator which is extremely simple in form, economical to manufacture and which may be easily installed and removed; the provision of a piston expander which is adapted to remove the piston slap in cast iron or semi-steel pistons of the full skirt type or of the slipper type as well as in aluminum trunk type pistons with various forms of slotted skirts; the provision of a piston expander which is firmly retained in position in the piston after once being installed; and the provision of a piston expander which may be easily manufactured in sizes to give a graduated scale 'of expansion pressures.

The above and other objects of my invention will appear from the following description of several embodiments thereof, reference being had to the accompanying drawing, in which- Figure 1 is a detached plan view of my combined piston skirt expander and pin noise eliminator.

Figure 2 is a side elevation of the device shown in'Figu're 1.

Figure 3 is an end elevation of. the device shown in Figures 1 and 2. I

Figure 4 is a vertical cross-sectional view through a piston, the connecting rod being shown in position, and the expander being preliminarily positioned ready for final installation.

Figure 5 is a vertical cross-sectional view of a full skirt type of piston with my expander installed.

Figure 6 is a view of the piston and expander shown in Figure 5 taken looking into the bottom end of the piston;

Figure 7 is a side'elevation of a piston having a. U slot skirt with my expanderinstalled.

Figure 8 is a bottom view of the piston and expander shown in Figure 7.

Figure 9 is a vertical, cross-sectional view through a type of heavy solid skirt piston having an annular ridge extending'around its inner circumference and having one of my expanders installed in engagement with this ridge. 4

Figure 10 is a bottom view of the piston and expander shown in Figure 9.

Referring particularly to Figures 1, 2 and 3, my expander comprises a generally U or arch shaped spring steel ribbon l which, for usual automobile internal combustion engine pistons, may be approximately /1" to wide and have a thickness of from about .012" to .024", depending, of course, upon the size of the piston and the pressure required of the expander.

The open ends of the U shaped spring steel member I are notched or cut out, preferably in V form as seen at 2, in order properly to engage the piston pin, as will be later explained. Se-

cured to the spring I on its curved portion at the bottom of the U shape is an outwardly projecting boss or spool generally indicated at B. This spool includes a shank portion which extends through a hole in the spring I and is riveted over as seen at 3, or secured to the spring I in any other suitable manner, as by welding, bolting, etc. The projecting portion of the boss B includes a stud 4 and a grooved portion 5. It will be understood, of course, that the proportions and general contour of the spring I and the boss member B may be modified without departing from the spirit of my invention. The curve of the closed end of the U shaped spring I, as illustrated, is substantially semicircular but other curved shapes may be given to the spring so long as it is provided with a pair of open ends which may engage the piston pm.

Itwill be noted that the stud 4 has a relieved diameter just large enough to accommodate the stud 4 which is preferably approximately in diameter for the usual automobile engine piston, A screw driver I0, or other suitable tool.

is inserted in the groove 5 on the boss B and the device is pushed up into the position shown iii-Figure 5 with a stud 4 snapped into the hole in the piston skirt. The length of the U- shaped expander spring I is such that, in order ,to push the expander up into operating position shown in Figure 5 from the position shown in Figure 4, it is necessary to compress the spring I by flattening out the U-shaped contour thereof. This is effected by engagement of the relieved or beveled edge 6 of the stud 4 with the wall of the piston skirt. The rounding or beveling of the edge of the stud 4 facilitates sliding thereof on the piston skirt and prevents gouging of the skirt wall thus assisting in the easy installation of the device. It will be seen that the boss B prevents the spring I from striking the piston skirt during installation as it projects out enough to cause the edge of the curved end of the spring I to clear the skirt as it is swung about the piston pin 9 into operatin position.

When the stud 4 snaps into the hole 8 the shoulder between the stud 4 and the grooved portion 5 of the boss B engages the piston skirt and, due to the length of the spring member I, a skirt expanding force is exerted by the spring I between the piston pin 9 and the skirt wall. It

. will be observed that the entire spring force is applied at a very small area on the skirt and thus I am able, by use of a relatively light spring, to distort the skirt wall sufficiently to cause the piston to fit properly in the cylinder and remove piston slap. The point. of application of the expanding force is located at a substantial distance below the piston head II. This is made possible by the provision of the boss or spool B. The advantages of this arrangement will be observed when it is noted that, if an expander spring is used bearing directly'against the skirt wall, as

in the ease of several commercial piston expand- I ers now in use, having springs extending entirely across the piston and bearing against opposite sides of the skirt, the spring force will be distributed along a vertical line from a point close to the piston head, where distortion of the skirt is virtually impossible, to a point well below the center of the piston pin. With these prior devices this arrangement is necessary in order to get the necessary expanding pressure even for the relatively flexible split skirt pistons with which such devices are intended to be used. By use of a narrow spring member I and the projecting boss or spool member B I have provided a piston expander which engages at its .open ends a fixed portion of the piston assembly and which may be swung up into operating position without the necessity of .excessive contraction or bending of the spring member I during installation. It will be seen that if a wide spring were used, or if the boss B were not employed, it would be impossible to move the expander from a position such as shown in Figure 4 into operating position without excessive distortion or compression of the spring. With my device the compression necessary for installation is maintained at a minimum and thus the maximum expanding force is available after the de vice is installed in operating position. It is, of course, necessary that the length of the expander spring I be such that, when the expander is installed as shown in Figures 5 and 6, the spring 'I will be under sufficient compression to give the desired expansion of the piston skirt.

In the application of my device to internal combustion engine pistons I have found that, when installed, my expander will be compressed radially of the piston from to By making the expander springs in lengths varying by approximately I am able to provide a series of expanders which will fit any piston and, for any given piston, will enable the mechanic to give varying degrees of expansion depending upon the length of expander spring employed. Spring pressures applied against the skirt by the boss B may vary from 20 pounds to 10.0 pounds or more and I have found that these pressures are ample to distort even solid skirt cast iron pistons into the necessary oval shape to eliminate piston slap. By means of the varying length expander springs I am able to apply an expander to a piston which will give the necessary expansion but which will not create an excessive drag.

My expander may be easily installed by driving it in with a light hammer and screw driver until the lug or spool enters the hole in the piston skirt and it may be removed by inserting a screw driver in the slot 5 and prying it out until the lug is removed from the hole. When the expander is 'in operating position it extends radially of the piston between the piston pin and the piston skirt, applying a pressure radially both against the piston pin and against the inner piston skirt wall. This results not only in the removal of piston slap but also in the complete elimination of piston pin noise in the type of engines where the piston pin is locked toy and movable with the connecting rod and moves freely in bearings in the piston pin bosses I2. Thus, any pin noise caused by wear of the pin ends or the bearings in the piston is removed due to the fact that the pin is resiliently held against the side of its bearings in the piston bosses by the spring I. My device is also eifective in reducing noise in piston assemblies of the type in which the pin is loose both in the piston bosses and in the connecting rod as, in such constructions, looseness which may occur due to wear most commonly takes place between the ends of. the pin and the piston bosses because the connecting rod bearing is usually very broad and is well lubricated and well backed.

With my expander and the V-notch and construction illustrated in the drawing the spring member engages the piston pin at four points in all, two on each side of the connecting rod. I have determined that even after as much as 50,000 miles of operation the only wear between the ends of the expander spring and the piston pin is that the spring may be worn in from .001" to .025 at each point of contact while the wear on the piston pin is merely a polish-which can be measured only in ten thousandths of an inch stantially in a radial direction I prefer that the side surfaces of the notched ends of the expander spring engage the end faces of the top of the connecting rod rather than the faces of the piston pin bosses. In all cases the thrust is directed against the pin and it is not necessary for the expander spring to engage the bosses, although in some instances, due to the width of the top end of the connecting rod or to the size of the piston, the springs maytouch lightly against the faces of the pin bosses.

In Figures 7 and 8 I have illustrated my invention as applied to a piston of the U-slot" type. In this installation a hole I3 is drilled in the piston skirt opposite the center line of the piston pin and the spring force of the expander H is exerted through the boss or lug l5 against the portion it of the piston skirt. The expander spring M is illustrated as being more curved in contour than that of Figure 6 and it will be seen that the ends of the expander engage the end faces of the top end I1 of the connecting rod.

The installation and removal of the expander shown in Figures '7 and 8 is the same as that shown in Figures 5 and 6. A somewhat longer projecting stud or lug is provided on the boss l5 as the skirt of the piston of Figures 7 and 8 has a thicker wall than that of the piston shown in Figures 5 and 6.

Figures -9 and 10 illustrate a modification of my expander which is particularly adapted for use with the type of solid skirt pistons which have an inwardly extending rib l8. With this type of piston the boss I9 is provided with a horizontally extending slot 20 instead of with a projecting lug as in the expander shown in Figures 1 to 8. The boss I9 is provided with an annular groove 21 which performs the same functions as the groove 5 of the expander shown in the other figures. In installation of the expander spring 22 a screw driver or other tool is inserted into the slot 2| and the device is driven into position until the boss I 9 slides over the flange or rib l8 and snaps into position, as shown in Figure 9, with the groove 20 engaging the flange l8.

In some instances it may be found desirable to install my expander with the ends of the spring member engaging the piston pin bosses rather than the piston pin. or course such installations will not remove pin noise but the other advantages obtained by my curved spring and projecting boss construction are still obtained.

Although I have described the illustrated embodiments of my invention in considerable detail it will be understood by those skilled in the art that modifications and variations may be made in the specific form of my expander and pin noise remover to accommodate the device for use with difi'erent types of pistons without departing from the spirit of my invention. I do not, therefore, wish to be limited to the specific forms of my invention illustrated and described but claim as my invention all embodiments thereof coming within the scope of the appendedclaims.

I claim: a

1. In a piston skirt expander and pin noise eliminator, a generally Ushaped spring member having notched ends adapted to engage a piston pin, and a boss secured to and extending outwardly from the midportion of said U-shaped spring, said boss having a portion adapted to engage and exert outward pressure against a piston skirt, the length of said portion being not greater than the skirt Wall thickness of the piston slot being adapted to receive an installing and removing tool.

2. In a piston skirt expander and pin noise eliminator, a generally U-shaped spring member having notched ends adapted to engage a piston pin, and a' boss secured to and extending outwardly from the midportion of said U-shaped spring, said boss havinga portion adapted to engage and exert outward pressure against a piston skirt but not to project beyond the outer surface thereof and a slot disposed in said boss between said skirt engaging portion and said spring member, said slot being adapted to receive an installing and removing tool, said skirt engaging portion of said boss having its edges relieved or chamfered.

3. In combination with a piston pin and piston having a skirt portion, a piston expander and pin noise eliminator comprising a curved spring memized expanding force through said boss against said skirt. a

4. In combination, a piston, a piston pin in said piston, and a piston expander and pin noise eliminator, said expander and pin noise eliminator comprising a generally U-shaped spring member having spaced notched ends engaging said piston pin, and a boss secured to the midportion of said U-shaped spring and having lockingengagement with the wall of said piston, said boss being disposed entirely within the outer surface of the piston skirt.

5. In combination, a piston, a piston pin in said piston, and a piston expander and pin noise eliminator, said expander and pin .noise eliminator comprising a generally U-shaped spring member having spaced notched ends engaging said piston pin, and a boss secured to the midportion of said U-shaped spring having locking engagement with the wall of said piston, and being disposed entirely within the outer surface thereof said boss extending out from said spring member sufficiently far to permit said spring member to be swung around said piston pin into working position without striking the piston skirt.

6. In combination with a piston having a skirt portion and a piston pin, spring means for exerting a force between the inner surface of the skirt and the pin tending to move said skirt outwardly in one direction and said pin in the opposite direction whereby said skirt portion is expanded and a force is'simultaneously exerted on said pin tending to eliminate noise, and means for locking said spring means in position in the piston.

7. In a piston skirt expander and pin noise eliminator device, a generally U-shaped spring member having notched ends adapted to engage a piston pin, and having a convexly curved portion between said notched ends, a bosssecured to said spring member and projecting outwardly ihe device is swung about the piston pin into operating position but not suflicient to extend through the skirt of the piston.

8. In a piston skirt expander and pin noise eliminator device, a generally U-shaped spring having notched ends connected by a convexly :1: zrved portion, a boss projecting from the outer ".rface of said curved portion, the length of said pring and boss being such that when said notched ends of said spring engage the piston pin of a piston in which the device is to be installed sad boss will project into but not through an a:-erture in the piston skirt radially opposite said pm, and said spring will exert pressure between the piston skirt and the piston pin whereby said skirt will be distorted and said pin will be urged away from the part .of the piston skirt engaged by said boss.

9. In a combined piston skirt expander and pin noise eliminator device, a lU-shaped spring member having spaced ends recessed to engage a piston pin and a convexly curved portion connecting said ends, and a locating and locking boss secured to and extending outwardly from said curved portion in a direction away from said ends, said boss being adapted to extend into but not through the skirt of a piston in which the device is to be installed, and said boss being adapted to lock and retain the portion of said U-shaped spring immediately adjacent the point of attachment of said boss thereto against movement relative to the piston skirt when the device is installed in a piston.

10. In combination with a piston having a skirt portion and a piston pin, spring means for exerting a force between the inner surface of the skirt and the pin tending to move said skirtoutwardly in one direction and said pin in thejopposite direction, whereby said skirt portion isexpanded and a force is simultaneously exerted on said pin tending to eliminate noise.

DEAN M. SOLENBERGER. 

